Line length is all about the ease of reading for the user. If a line of text is too long, it becomes more difficult for the user to stay engaged with the content of the web page. By following the rules of line length, which is the amount of character, including spaces, designers can help keep a smooth reading experience, make the content more accessible, and keep the user more engaged.
Some of the solutions that designers can use to help users, is by limiting the amount of characters per line. The ideal amount of characters is 45 to 75 characters per line for desktop and 30 to 50 characters per line for mobile devices. This character range helps make it easy for the use to read without straining their eyes. The shorter lines can also help break up the reading flow. Longer lines can make it more difficult to keep track of where you are in the text.